Heretofore, when refrigerant-charged refrigeration systems, such as automotive air conditioning systems, were repaired, the refrigerant charge was simply vented to atmosphere to accomplish the repairs. More recently, it has become increasingly important to capture and reuse the refrigerant charge in such refrigeration systems, both to avoid pollution of the atmosphere and to minimize the increasing costs of disposal and replacement of the refrigerant charge. As used herein, “recover” means to remove used refrigerant from refrigeration equipment and collect it in an appropriate external container. “Recycle” means to reduce the amount of contaminants in used refrigerant so that it can be reused. Systems for recovering and recycling used refrigerant typically extract it from a refrigeration system in gaseous form, remove oil and moisture from the refrigerant, condense the refrigerant to liquid form, and store it in a recovery tank.
A block diagram of a conventional refrigerant recovery/recycling system, in the form of a vehicle air conditioning maintenance system, is shown in FIG. 1. The air conditioning maintenance system 100 includes ports 101, 102 which are respectively connected to the high pressure side and low pressure side of a refrigeration system, such as a vehicle air conditioning system (not shown). A compressor 110 pulls the refrigerant from the air conditioning system through the ports 101, 102, past gauges 103, 104, and valves 105, 106 into an evaporator/oil separator 120, also called an accumulator. In accumulator 120, any lubricant (usually an oil) which has flowed along with the refrigerant from the vehicle to the maintenance system 100 drops to the bottom of its oil separator. At the end of a recovery operation, any oil that has been collected is drained into a bottle. Accumulator 120 becomes cool during operation, because liquid refrigerant in accumulator 120 changes to the gaseous phase as it passes through. In fact, conventional accumulators 120 can become cold enough for ice to form on their outer surfaces. However, accumulator 120 is more efficient when warm. Consequently, a heat blanket (not shown) or the like is usually employed to warm accumulator 120 to help vaporize any liquid refrigerant.
The vaporized refrigerant is pulled out of accumulator 120 and passes through filter/dryer 130, where any moisture is removed, before entering the suction side of compressor 110. Refrigerant is pushed out of compressor 110 as a high-pressure, high-temperature gas. Some of compressor 110's oil may be pushed out in solution with the refrigerant. The refrigerant and oil from compressor 110 flows into the top of a compressor oil separator 111, where any oil drops to the bottom and is later returned to compressor 110 via a solenoid 112.
The pressurized, hot vaporous refrigerant then flows through a check valve 113 and into the finned tubing of a condenser 140. A fan (not shown) pushes relatively cool ambient air through the fins of condenser 140, which transfers heat from the refrigerant to the atmosphere, causing the gaseous refrigerant to condense into a liquid. The liquid refrigerant then flows to a recovery tank 150.
Accumulator 120 becomes cool when operating, but is more efficient when warm. Conversely, condenser 140 and recovery tank 150 are heat-producing components that are more efficient when cool. Moreover, when operating in high ambient temperatures, the efficiency of conventional refrigerant recovery/recycling systems decreases significantly. To meet efficiency goals over a range of operating temperatures, conventional systems warm their accumulators using a heat blanket and cool their condensers using a fan and air flow controls, which consume energy and complicate the system, thereby raising the cost of production and operation. There exists a need for an apparatus and methodology for a simplified, less costly, more efficient refrigerant recovery/recycling system.